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The catalytic performance of CeO2is closely related to its surface oxygen vacancy, and the formation of surface oxygen vacancies on different facets is expected to be varied significantly. To investigate the generation and properties of oxygen vacancies on the {111} facet with a high formation energy of oxygen vacancies, nanosized CeO2polyhedrons with exposed {111} facets were reduced at different temperatures with H2. In situXPS, 1H MAS NMR, 31P MAS NMR with trimethylphosphine (TMP) as the probe molecule, 1H–31P CP/MAS NMR, and 17O MAS NMR with H217O were performed to characterize the oxygen vacancies on the surface of the reduced CeO2-polyhedron. The results indicate that the content of surface hydroxyl groups decreases gradually when the reduction temperature rises. Surface oxygen vacancies are generated at 350 °C and the maximum amount of surface oxygen vacancies are obtained at 400 °C. Further rising of the reduction temperature leads to the structural reconstruction on the surface of CeO2-polyhedron. Moreover, the longitudinal relaxation time (T1) of 31P nuclei of TMP adsorbed on the CeO2-polyhedron surface is significantly reduced after the formation of surface oxygen vacancies. The adsorption models of TMP on the CeO2-polyhedron surface are established according to characterization results, and the content of surface oxygen vacancies is obtained quantitatively.

Pseudolaric acid B (PAB) is the most active constituent extracted from the bark of Pseudolarix kaempferi, which has been used as an antifungal remedy in traditional Chinese medicine. It is reported to have cytotoxicity to many tumor cell lines. In this study, we investigated the effects of PAB against human endometrial cancer Ishikawa cells. We found that PAB inhibited Ishikawa cell proliferation, and induced cell apoptosis and G2/M phase arrest through a mechanism involving AKT-GSK-3β and ERK1/2 signaling pathways. PAB also suppressed the Ishikawa cell adhesion, invasion, migration, and colony formation ability by increasing the expression of E-cadherin, Ezrin, and Kiss-1, and decreasing the expression of matrix metalloproteinase-9 and vascular endothelial growth factor. Taken together, these data indicated that PAB can be expected to be a novel treatment agent for endometrial cancer therapy.

The surface oxygen vacancy of metal oxide is a type of important catalytic active site. To investigate the origin and nature of oxygen vacancy, CeO2nanorods with exposed {110} facets were treated at different temperatures under H2atmosphere. 1H MAS NMR, 31P MAS NMR with trimethylphosphine (TMP) as the probe molecule, in situ XPS, and in situ EPR were employed to characterize the surface oxygen vacancy of the reduced samples. The results show that the decrease of the hydroxyl group content and the increase of Ce3+concentration occur gradually with the increase of reduction temperature. When the temperature reaches 350 °C, the surface and bulk oxygen vacancies of CeO2are generated. The longitudinal relaxation time (T1) and the motion of 31P nuclei from TMP molecules adsorbed on the CeO2surface were found to be significantly reduced with the formation of surface oxygen vacancies. Based on the characterization results, the adsorption models of probe molecules on the surface of the samples are established and the amount of surface oxygen vacancies can be estimated quantitatively.

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